The megapodes, also known as incubator birds or mound-builders, are stocky, medium-large chicken-like birds with small heads and large feet in the family Megapodiidae. Their name literally means large foot (Greek: mega = large, poda = foot), and is a reference to the heavy legs and feet typical of these terrestrial birds. All are browsers, all but the Malleefowl occupy wooded habitats, and most are brown or black colored. Megapodes are superprecocial, hatching from their eggs in the most mature condition of any birds. They hatch with open eyes, with bodily coordination and strength, with full wing feathers and downy body feathers, able to run, pursue prey, and, in some species, fly on the same day they hatch.[1]

Contents

Megapodes are medium-sized to large terrestrial birds with large legs and feet with sharp claws. They range from 28 to 70 cm. The largest members of the clade are the species of Alectura and Talegalla. The smallest are the Micronesian Scrubfowl (Megapodius laperouse) and the Moluccan Scrubfowl (Eulipoa wallacei). They have a small head, a short beak and rounded and large wings. The flying abilities vary within the clade. They present the hallux at the same level of the others toes just like the species of the clade Cracidae. The others Galliformes have an hallux that is raised above the level of the front toes.
[2]

Megapodes are mainly solitary birds that do not incubate their eggs with their body heat as other birds do, but bury them. Their eggs are unique in having a large yolk, making up 50-70% of the egg weight.[3] They are best known for building massive nest-mounds of decaying vegetation, which the male attends, adding or removing litter to regulate the internal heat while the eggs hatch. However, some bury their eggs in other ways: there are burrow-nesters which use geothermal heat, and others which simply rely on the heat of the sun warming sand. Some species vary their incubation strategy depending on the local environment.[4] Although the Australian Brushturkey is the only species of bird in which sex ratio is confirmed to be incubation-temperature dependent, it is speculated that this is common to all Megapodes, as they share nesting methods unique among birds.[5] The non-social nature of their incubation raises questions as to how the hatchlings come to recognise other members of their species, which is due to imprinting in other members of the order Galliformes. Recent research suggests that there is an instinctive visual recognition of specific movement patterns made by the individual species of megapode.[6]

Megapode chicks do not have an egg tooth: they use their powerful claws to break out of the egg, and then tunnel their way up to the surface of the mound, lying on their backs and scratching at the sand and vegetable matter. Similar to other superprecocial birds, they hatch fully feathered and active, already able to fly and live independently from their parents.[3]